A contraction for the full word Ramen-gasm.
A R'asm is an orgasm brought upon by either the consumption of a great deal of Ramen or consumption of some of the world's best Ramen. Ramen is a food considered by most to be incredibly amazing.
R'asms are incredibly rare, and very few people actually have the ability to have one. Those who can consider themselves very lucky, as they claim it is "an unforgettable experience, one you just can't live without once you've had it".
Under rare circumstances, people have had documented R'asms while eating Top Ramen, but never while eating Cup Noodles.
"Hey dude, want some Ramen? It's so good, I just R'asmed in my pants."